Absorption refrigeration system



May 5, 1970 J. ROEDER, JR 3,509,732

ABSORPTION REFRIGERATION SYSTEM Filed Oct. 20, 1965 2-Sheets-Sheet 1 ooooooo IN V E N TOR Mfiede 7/454 261., My fit- @1/ A TTOR/VEYS May 5, 1970 J. ROEDER, JR

ABSORPTION REFRIGERATION SYSTEM Sheets-Sheet 2 Filed Oct. 20, 1965 United States Patent 3,509,732 ABSORPTION REFRIGERATION SYSTEM John Roeder, Jr., Benton Harbor, Mich, assignor to Whirlpool Corporation, a corporation of Delaware Filed Oct. 20, 1965, Ser. No. 498,235

Int. Cl. F25b 15/00 US. Cl. 62476 7 Claims This invention relates to an absorber-heat exchanger apparatus for a liquid-gas refrigeration system.

In one well-known form of refrigeration system refrigerant gas such as ammonia is absorbed in a liquid such as water in an absorber portion of the system. One of the features of the the present invention is to provide an improved absorber-heat exchanger apparatus for such a system.

Another feature of the invention is to provide an improved apparatus in such a system for heat exchange between liquid refrigerant flowing to an evaporator and gaseous refrigerant flowing from the evaporator together with improved means for retarding the flow of gaseous refrigerant into the liquid refrigerant portion of the heat exchanger to prevent this portion operating as a condenser which would retard flow of liquid refrigerant through the heat exchanger.

Other features and advantages of the invention will be apparent from the following description of one embodiment thereof taken in conjunction with the accompanying drawings. of the drawings:

FIG. 1 is a semi-diagrammatic representation of a liquid-gas refrigeration system having parts thereof embodying the invention and with certain parts shown in section and others in side elevation.

FIG. 2 is a side elevational view of an absorber-heat exchanger portion of the apparatus.

FIG. 3 is a plan view of the apparatus of FIG. 2.

FIG. 4 is a plan view of the separated bottom part of the apparatus of FIG. 2.

FIG. 5 is a side elevational view of the part of FIG. 4.

In the representation of the entire system as shown in FIG. 1 there is prvidod a generatr shown here semi-diagrammatically but described more fully and claimed in the copending application of B. A. Phillips, Ser. No. 502,186, filed Oct. 21, 1965, assigned to the same assignee as the present application.

The generator 10 is in the form of a vertical cylinder that is heated on the bottom by a gas burner 11 providing a circle of flame .12 around the bottom of the generator. For more efficient heat transfer the lower sides of the generator 10 are provided with spaced vertical vanes 13 with additional vanes 14 provided above the vanes 13.

The apparatus includes an absorber 15 which is in two principal parts with one part being a vertical heat exchanger 16 and the other part 36 being a coil absorber portion of the type disclosed and claimed in the copending application of E. P. Whitlow et a1. Ser. No. 370,269, filed May 26, 1964, also assigned to the same assignee as the present application.

The generator 10 is of a flooded type and when in operation is filled to slightly below an an inlet pipe 17 for liquid rich in dissolved refrigerant. In the generator 10 the dissolved refrigerant such as ammonia is boiled off and rises to the top 18 of the generator as a gas, as indicated in FIGURE 1. This gas flows through an out- 3,509,732 Patented May 5, 1970 wardly extending tube 19 that forms a part of a heat exchanger 20 and from there flows through a pipe 21 to an ordinary condenser 22 of the type illustrated in E. P. Whitlow copending application Ser. No. 370,327, filed May 26, 1964, now Patent 3,236,064, and also assigned to the same assignee as the present application.

In the condenser 22 the gaseous refrigerant is converted into liquid refrigerant and the liquid refrigerant flows outwardly through a pipe 23 and a flow restrictor such as a capillary 24.

After flow through the capillary 24 the liquid refrigerant passes through the internal helical coil 25 of a heat exchanger 26. On leaving the coil 25 of the heat exchanger the liquid refrigerant passes through a second flow restrictor such as the capillary 66 into the evaporator 27 which is chilled by evaporation of the liquid refrigerant therein in the customary manner. This evaporator 27 is surrounded by a liquid 28 such as water plus an antifreeze material in a container 29 to chill the liquid. The liquid is then pumped by means (not shown) in the customary manner to the desired location for providing a desired cooling effect at this location.

In the evaporator 27 the liquid refrigerant of course evaporates and becomes gaseous refrigerant. This gaseous refrigerant flows from the evaporator through a pipe 30 into the interior 31 of the heat exchanger 26 where it passes over the coil 25 containing the incoming liquid refrigerant, as previously described, in heat exchange relationship therewith.

From the heat exchanger 26 the gaseous refrigerant or rich gas flows through the pipe 32 into the heat exchanger portion 16 of the absorber. This portion of the apparatus will be described in greater detail hereinafter.

In the absorber portion 16 the rich gas from the pipe 32 is partially absorbed in weak liquid flowing into the absorber portion 16 through the outlet pipe 33 and capillary 34 from the generator 10.

Partial rich liquid and unabsorbed refrigerant gas flow from the bottom of the absorber portion 16 through the plurality of pipes 35 respectively connecting to inlets to the coil portion 36 of absorber 15. In this coil portion 36 absorption is complete so that the liquid flowing from the absorber portion 36 through the pipe 37 is liquid rich in dissolved refrigerant.

The rich liquid from the absorber 15 flowing through the pipe 37 enters a receiver 38 and is pumped by means of a pump 39 up a pipe 40 to the heat exchanger 20'. The pump 39 is a diaphragm which is operated by hydraulic fluid supplied through a line 41.

The rich liquid from the pipe 40 flows through a helical coil 42 in the heat exchanger 20. The rich liquid in this coil flows countercurrently in heat exchange relationship to the hot refrigerant gas flowing outwardly through the tube 19 in a manner previously described. With this arrangement the rich liquid is heated and the hot gas from the generator is cooled before passing to the condenser 22 in the manner previously described.

From the heat exchanger 20 at the top of the generator the rich liquid flows through a pipe 43 to the bottom of a vertical helical coil 44 forming a part of the heat exchanger portion 16 of the absorber 15. From the top of this coil 44 the rich liquid flows through the rich liquid inlet pipe .17 to the generator 10 to complete the circuit.

A very important part of the liquid-gas refrigeration system described in the absorber-heat exchanger part 16 shown in detail in FIGS. 2-5 inclusive. This heat exchanger 16 comprises a vertical generally cylindrical container 45 closed at the top by a cap 46 and at the bottom by a similar cap 47. The helical coil 44 is arranged vertically and substantially concentrically within the cylinder 45 and spaced inwardly from the walls thereof.

Positioned within the cylinder 45 at the top thereof and above the top of the helical coil 44 is a first cup 48. Located within this first cup 48 is a second inverted cup 49 of smaller diameter than the first cup 48 and substantially concentric therewith. This second cup 49 is provided with a plurality of holes 50 adjacent its top and a plurality of cutout openings 51 at the bottom and within the confines of the sides of the first cup 48.

Extending through the bottom of the first cup 48 and above the coils of the helix 44 are a plurality of vertically extending small tubes 52 arranged generally in a circle. To avoid confusion, FIG. 2 illustrates only 2 of these tubes 52 with the two selected being located diametrically opposite each other. The top of each small tube 52 is provided with a hole 53 having an area less than the cross sectional area of its tube 52.

Weak liquid from the generator 10 and capillary 34 is directed into the interior of the second inverted cup 49 through a pipe 54 that is arranged tangentially to the cup 49 as illustrated most clearly in FIG. 3.

At the bottom of the absorber-heat exchanger apparatus 16 the rich gas pipe 32 previously described enters the coil 45 and extends upwardly as a pipe extension 55. This pipe extension 55 is substantially concentric with cylinder 45 and helical coil 44 and is provided with a sloped outlet end 56 substantially between the top of the helical coil 44 and the bottom of the first cup 48. This outlet end is sloped as shown in FIG. 2 in order that the end of this pipe will not be accidentally blocked by positioning the cup 48 against it in assembling the apparatus.

Extending downwardly from the cup 48 and located between the pipe extension 55 and the helical coil 44 is a tube 57. This tube 57 is spaced from both the coil 44 and the pipe 55 and is concentric with these and with the vertical cylinder 45. The lower end 58 of this tube is open adjacent the bottom of the cylinder 45.

The rich liquid pipe 43 previously described enters the apparatus 16 at the bottom and continues upwardly in the apparatus 16 as helical coil 44. The upper outlet end 59 of this rich liquid helical coil 44 is located at the top of the apparatus 16 and is attached to the rich liquid inlet pipe 17 of the generator 10 as previously described.

The tube 57 and the helical coil 44 are anchored to each other and held in spaced relationship as described above by three equally spaced spacers 60 at the top and bottom of the coil 44.

As previously described, the rich gas flows into the absorber portion 16 through the pipe 32. It leaves the pipe extension 55 at the outlet end 56 that is adjacent the top of the tube 57 and then flows downwardly in the tube 57 in the space between the tube and the pipe extension 55. Non-refrigerant gases in the rich gas are bled out of the interior of the tube 57 through a small bleed hole 61 at the top of the tube.

The refrigerant gas flowing downwardly in the tube 57 leaves the tube at the lower outlet end 58. Here it mixes with the Weak liquid flowing over the helical coil 44 from the small upper tubes 52 so that the refrigerant gas becomes partially absorbed in the weak liquid. The resulting liquid and refrigerant gas then flows through the pipes 35 into the coil portion 36 of the absorber 15.

In the embodiment illustrated there are four of these pipes 35, each having an inner end 62 within the bottom of the cylinder 45. In order to illustrate these inner ends 62 more clearly, FIGS. 4 and show the bottom cap 47 of the cylinder and the ends of the pipes 35 attached thereto.

As is shown in FIG. 5, each inner end 62 of the pipes 35 contains a plurality of small holes 63, here shown as four. The holes or liquid openings 63 are formed along the axis of the respective pipes 35 and are preferably all of the same size. The respective holes are horizontally aligned with the corresponding holes of the other pipes so that each pipe has the same number of liquid openings at a given liquid level in the bottom of the cylinder 45. This arrangement thus provides means for metering the flow of liquid into the pipes 35 so that each of them carries a substantially equal portion of the fluid to the coil portion 36 of the absorber 15. In addition, the above-described metering means effectively prevents slugging of liquid into the coil portion 36 of the absorber 15. Liquid slugging would occur if the openings 63 were not included and liquid was forced to enter the pipes 35 through the vapor entry openings at the ends of the pipes.

The capillary 34 in the weak liquid outlet pipe 33 from the generator 10 separates the high pressure interior of the generator from the relatively low pressure absorber. Thus, in one embodiment this capillary lowered the pressure from 300 p.s.i. in the generator to about 55 p.s.i. in the absorber. The weak liquid flowing through the pipe 54 into the first cup 48 rises in this cup to the tops of the circularly arranged vertical tubes 52. The liquid then flows through the small openings 53 the tops of the vertical tubes 52 and down onto the top turn 64 of the helical coil 44. This weak liquid absorbent solution flows down over the successive turns absorbing refrigerant gas on the way and collects in a pocket at the bottom of the cylinder and within the bottom cap 47. The mixture of partial rich liquid and unabsorbed refrigerant gas then enters the pipes 35 by way of the plurality of small holes 43 and the pressure of the refrigerant gas in the pipes 45 forces the mixture of partially strong liquid and refrigerant gas through the pipes 45 into the coil portion 36 of the absorber 15.

As mentioned earlier, the weak liquid passage 54 enters the inverted cup 49 at the top of the absorber part cylinder 45 at a tangent. The liquid falls to the bottom of the inverted cup and flows out through the openings 51 into the larger cup 48 for flow over the helical coil 44 as described. The refrigerant gas in the weak liquid within the cup 49 flows outwardly through the top openings therein. The small openings 53 at the top of each vertical tube 52 are provided so that the flow through the series of tubes is substantially uniform. It is much easier to have uniform sizes in the series of small openings 53 than it is to provide uniform diameters to the small tubes 52. If the small openings were not substantially the same size and one was substantially larger than the others this one would tend to siphon off most of the liquid so that flow down and over the turns of the helical coil 44 would be non-uniform. The small openings 53 at the tops of vertical tubes 52 have an additional advantage in that it is much more difficult for oil and other contaminants to interfere with the liquid flow through the openings 53 than it would be through the tubes 52. In one construction these drip tubes 52 were not spaced directly above the center of the topmost turn 64 of the coil 44 'but were staggered on opposite sides of the center in order to get even distribution of liquid on both sides of the coil. It was found in actual production that it was almost impossible to center each tube 52 over the helical coil 44. Therefore, they were deliberately offset from the center but staggered as described.

As briefly described earlier, the capillary 24 at the entrance to the heat exchanger 26 is used to retard entry of gaseous refrigerant from the condenser 22 into the coil 25 within the heat exchanger 26. If this should occur, the coil 25 would then function as a condenser to condense this unwanted gaseous refrigerant. During any operation of coil 25 as a condenser, flow of liquid refrigerant through the heat exchanger 26 to the evaporator 27 would be interferred with. Furthermore, to make matters worse, if the coil 25 were operating as a condenser it would continue to do so as the reduced pressure brought about by the condensing action would draw more refrigerant gas from the condenser. This would occur also because the condenser 22 is on the high pressure side of the system. This malfunctioning of the coil 25 portion of the liquid refrigerant pipe 23 has been found in practice to occur at any time if the temperature of the liquid 28 surrounding the evaporator 27 is within 2 F. of the temperature in the evaporator 27. When this small temperature difference occurs, some of the liquid refrigerant will not evaporate in the evaporator 27 but will flow through the outlet pipe 30 into the interior 31 of the heat exchanger 26. This will have the eflfect of subcooling the outlet end of the liquid refrigerant coil 25 in the heat exchanger 26. This would tend to further draw gaseous refrigerant from the condenser 22 into the heat exchanger 26 so that it would malfunction as a condenser, as previously described.

By providing the capillary 24 in the liquid refrigerant line 23 at the entrance to the helical coil 25 this flow of gaseous refrigerant into the coil is substantially prevented. Similarly, the providing of a second capillary 66 at the outlet end of the heat exchanger coil 25 and before the evaporator 27 also retards flow from the condenser 22 to the evaporator 27 with the result that the flow of gaseous refrigerant into the coil 25 is further retarded. Thus, the capillaries 24 and 66 function together to prevent substantially the flow of gaseous refrigerant into the heat exchanger coil 25 so that it cannot function as a condenser.

As is shown in FIG. 1, the exit end 56 of the rich gas pipe 32 is at a relatively high level. The volume of liquid storage in the absorber vertical heat exchanger 16 below exit end 56 is greater than the volume of liquid leaving the generator 10. This arrangement is provided so that when the system is shut off weak liquid cannot enter the pipe 32 and flow into the evaporator 27. If weak liquid did happen to fill the evaporator 27 it would take a considerable time after again starting up the apparatus for the rich gas flowing through the tube 19 and pipe 21 to convert the weak liquid in the evaporator to rich liquid and build up enough pressure to force the weak liquid from the evaporatori Furthermore, if this occurred, there would be considerable danger of the generator overheating in its attempt to build up enough refrigerant gas pressure to force the liquid out of the evaporator.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.

The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows:

1 Absorber-heat exchanger apparatus for a liquid-gas refrigeration system, comprising: means providing a chamber; enclosed liquid conduit means having an outer surface within said chamber, said conduit means being in the form of a substantially vertical helix within said chamber; means for flowing a weak absorbent solution over the outer surface of said coil in heat exchange relationship therewith comprising a liquid distributing cup member above the topmost individual coil in said helix having a plurality of outlets above the topmost coil for flowing said solution over said topmost coil and then succeeding coils; and means for supplying to said chamber a gaseous refrigerant in contact with said solution to enrich the solution.

2. The apparatus of claim 1 wherein each said conduit member has an entrance opening for said solution smaller than the cross sectional area of its conduit member.

3. The apparatus of claim 1 wherein said liquid receiving member comprises a first cup in said chamber in which said plurality of conduit members are located and an inverted second cup within said first cup having spaced liquid flow means communicating with said first cup and gaseous flow means communicating with said chamber, and said means for flowing said solution comprises a conduit emptying into said second cup.

4. Absorber-heat exchanger apparatus for a liquid-gas refrigeration system, comprising: means providing a chamber; enclosed liquid conduit means having an outer surface within said chamber, said conduit means being in the form of a substantially vertical helix within said chamber; means for flowing a weak absorbent solution over the outer surface of said helix in heat exchange relationship therewith; and means for supplying to said chamber a gaseous refrigerant in contact with said solution to enrich the solution, said means for supplying said gaseous refrigerant comprising conduit means emptying into said chamber at an area adjacent the bottom of said helix, said conduit means comprising a first conduit in said chamber having an exit end adjacent the top of said helix and a second conduit enclosing but spaced from said first conduit having an exit adjacent the bottom of said helix.

5. Absorber-heat exchanger apparatus for a liquid-gas refrigeration system, comprising: means providing a chamber; enclosed liquid conduit means having an outer surface within said chamber, said conduit means being in the form of a substantially vertical helix within said chamber; means for flowing a weak absorbent solution over the outer surface of said coil in heat exchange relationship therewith comprising a liquid distributing member above the topmost individual coil in said helix hav ing a plurality of outlets located above said topmost coil for flowing said solution over said topmost coil and then succeeding coils, said liquid distributing member comprising a liquid receiving member having a plurality of conduit members providing said outlets, the liquid receiving member comprising a first cup in said chamber in which said plurality of conduit members are located and an inverted second cup within said first cup having spaced liquid flow means communicating with said first cup and gaseous flow means communicating with said chamber, and said means for flowing said solution comprises a conduit emptying into said second cup: and means for supplying to said chamber a gaseous refrigerant in contact with said solution to enrich the solution, said means for supplying said gaseous refrigerant comprising conduit means emptying into said chamber at an area adjacent the bottom of said helix and the conduit means comprising a first conduit in said chamber having an exit end adjacent the top of said helix and a second conduit'enclosing but spaced from said first conduit having an exit adjacent the bottom of said helix.

6. Absorber-heat exchanger apparatus for a liquid-gas refrigeration system, comprising: means providing a chamber; means for supplying to said chamber an absorbent solution; means for supplying to said chamber refrigerant vapor to contact the absorbent solution for partial absorption of the refrigerant vapor in the absorbent solution; a coil absorber for completing absorption of unabsorbed refrigerant vapor in the absorbent solution; and conduit means connecting said chamber to said coil absorber for transfer of fluid from said chamber to said coil absorber, said conduit means including means for metering fluid flow to insure equal distribution of fluid to all parts of said coil absorber, the coil absorber having a plurality of inlets, the conduits means comprises a plurality of pipes connecting to said inlets, and the means for metering fluid flow comprises means forming small liquid openings at the inlet ends of the pipes.

7. Absorber-heat exchanger apparatus as claimed in claim 6 wherein the means forming small liquid openings comprises a series of holes along the axis of each pipe, with the holes of each pipe being horizontally aligned with the corresponding holes of the other pipes so that each pipe has the same number of liquid openings at a given liquid level.

References (Iited UNITED STATES PATENTS 8 2/1963 Phillips et a1. 62494 X 3/1964 Leonard 62494 'X FOREIGN PATENTS Great Britain.

LLOYD L. KING, Primary Examiner US. Cl. X.R. 

1. ABSORBER-HEAT EXCHANGER APPARATUS FOR A LIQUID-GAS REFRIGERATION SYSTEM, COMPRISING: MEANS PROVIDING A CHAMBER; ENCLOSED LIQUID CONDUIT MEANS HAVING AN OUTER SURFACE WITHIN SAID CHAMBER, SAID CONDUIT MEANS BEING IN THE FORM OF A SUBSTANTIALLY VERTICAL HELIX WITHIN SAID CHAMBER; MEANS FOR FLOWING A WEEK ABSORBENT SOLUTION OVER THE OUTER SURFACE OF SAID COIL IN HEAT EXCHANGE RELATIONSHIP THEREWITH COMPRISING A LIQUID DISTRIBUTING CUP MEMBER ABOVE THE TOPMOST INDIVIDUAL COIL IN SAID HELIX HAVING A PLURALITY OF OUTLETS ABOVE THE TOPMOST COIL FOR FLOWING SAID SOLUTION OVER SAID TOPMOST COIL AND THEN SUCCEEDING COILS; AND MEANS FOR SUPPLYING TO SAID CHAMBER A GASEOUS REFRIGERANT IN CONTACT WITH SAID SOLUTION TO ENRICH THE SOLUTION. 